Power generators such as electric motors, internal combustion engines, and humans typically generate power most efficiently when operating within a narrow range of speeds, while a specific application for the power, a wheeled vehicle for example, might require a broad range of speeds. A transmission is often used to adapt the speed characteristics of the power generator to the speed characteristics of the power application. Many transmissions function, for example, as rotary speed changers. Transmissions are also used to convert one kind of motion to another kind of motion, converting a rotary motion input to a linear motion output for example. Transmissions may provide a torque-speed conversion from a higher speed motor to a slower but more forceful output, reducing the speed from the input to the output, or from a slower speed motor to a faster but less forceful output, increasing the speed from the input to the output. A continuously variable transmission (CVT) is a transmission in which the ratio of the torque and speeds of the input and the output can be varied continuously within a given range, providing an infinite number of possible torque-speed ratios within that range.